Such a rate of franking is at the present time not attained by any machine available on the market, due to the necessity of maintaining an optimum quality of printing for the postal indicia (which is a monetary value). In addition, in franking machines of the ink jet type, it is necessary to stop the ejection of the drops of ink regularly in order to scrape and clear the ejection nozzles to avoid accumulation of dirt and therefore blockage of the printing.
In order to increase the printing rates, U.S. Pat. No. 3,869,986 and European Patent Application EP 0 172 561 have proposed to separate the franking data into fixed data and variable data. However, although such a solution does allow an increase in the rates, it does not allow 20 000 and more envelopes to be processed due to the necessary periodic maintenance of the ink jet printing means.
It is an object of the present invention to overcome the drawbacks set forth hereinabove and to propose a high-rate franking machine of particularly high performance while remaining simple to use and, especially, which can ensure continuous operation.